N.B. The email exchange below may have been edited, e.g. to remove content not essential to the main point(s) or to standardize English spelling/grammar.
...Saying that [language X] is spoken in [area Y] is quite a geographic stretch, since [Y] is a large space and [X] is spoken only in [certain areas] which are inhabited by ethnic [speakers of X]...
... A critical observation that you seem not to have made... is that, when English speakers mention language X as being spoken in area Y, they do not mean any of:
For 'language' you may substitute 'dialect' with no change in truth value.
When we English speakers say that American English is spoken in the U.S., we do not mean that it is spoken in every U.S. locale (in some places Spanish is the lingua franca -- or Chinese, or Korean...); we do not mean that everyone in the U.S. speaks American English (many cannot); we do not mean that no American English speakers can be found elsewhere in the world (they are found all over, probably in every country); and we do not mean that no other language is spoken in the U.S. (many hundreds of languages are spoken here). Yet no one who is a native English speaker would argue with the statement, "American English is spoken in the U.S."
It is in this sense that English speakers can say "[language X] is/was spoken in [area Y]," and we will understand one another. We can also hear "[X] is spoken in the U.S." and know that it must imply some [presumably small] community of immigrant speakers of [X]; so this statement, too, is true -- only in a different way.